1.2.2 Exhaust Valves
DETROIT DIESEL 53
valve at the valve head must not be less than 1/32 " in thickness and must still be within the specifications shown in Figs.
11 and 12 after refacing.
Before either a new or used valve is installed, examine the valve seat in the cylinder head for proper valve seating. The
angle of the valve seat insert must be exactly the same as the angle of the valve face to provide proper seating of the
valve. The proper angle for the seating face of both the valve and valve seat insert is 30°.
When a new valve seat insert is installed or an old insert refaced, the work must be done with a grinding wheel (Fig. 10).
The eccentric grinding method for reconditioning valve seat inserts is recommended. This method produces a finer, more
accurate finish since only one point of the grinding wheel is in contact with the valve seat at any time. A micrometer feed
permits feeding the grinding wheel into the work .001 " at a time.
To grind the valve seat inserts for a four valve cylinder head, use the following tools:
Grinder J 8165-1
Dial Gage J 8165-2
Pilot J 7792-1
Grinding Wheel (15 °) J 7792-2
Grinding Wheel (30 °) J 7792-3
Grinding Wheel (60 °) J 7792-4
Grind the valve seat inserts as follows:
First apply the 30 ° grinding wheel on the valve seat insert.
Use the 60 ° grinding wheel to open the throat of the insert.
Then grind the top surface with a 15 ° wheel to narrow the width of the seat from 3/64 " to 5/64"
Fig. 10 · Grinding Valve Seat Insert
Fig. 11 - Relationship Between Exhaust Valve,
Insert and Cylinder Head (Two Valve Head)